There are many medical procedures which require the performance of one or more anastomoses in which a conduit such as a vessel, duct, graft or other tubular structure must be joined to another vessel, duct, or other hollow structure such as an organ to establish continuity between these structures. One of the more prevalent needs for improving anastomosis techniques lies with the treatment of coronary artery disease, where a stenosis of one or more coronary arteries prevents or seriously interferes with a normal blood supply to the heart tissue. In such situations, a total or partial blockage of a coronary artery is often treated by bypassing the obstruction in a heart bypass procedure, such as a coronary artery bypass graft (CABG) procedure, in which a graft is fluidly connected to the blood supply on opposite sides of the site of the stenosis to provide an alternate route for the blood to take on route to the heart.
The graft may be natural conduit, artificial conduit, or a combination of natural and artificial conduits. Typically, a natural conduit in the form of an autograft is used, wherein a saphenous vein is harvested from the leg of the patient or the internal mammary artery is rerouted to be anastomosed downstream of the site of the stenosis.
Conventional CABG procedures are currently performed while the beating of the heart has been stopped, with the circulation and oxygenation of the patient's blood being performed by a heart and lung bypass machine. This procedure requires significant manipulation and clamping of the aorta of the patient. Recently, it has been found that this procedure tends to increase the risk of dislodging plaque that may have accumulated on the internal wall of the aorta in the vicinity of the clamping. Dislodgment of plaque can cause emboli in various locations in the patient's body, cutting off the blood supply downstream of the locus of the embolus, which can cause a stroke or other serious medical complications. Further, the heart-lung bypass machine is thought to cause mechanical damage to the blood cells which furthers the risk of medical complications, due to potential clot formation.
Recently there has been an increase in the performance of beating heart CABG procedures, in which the bypass of one or more stenoses is performed while the patient's heart continues to beat, with the circulation and oxygenation of the patient's blood being performed naturally by the heart and lungs of the patient. While beating heart procedures reduce the associated risks of stroke and other post-operative complications associated with the clamping and manipulation of the aorta and the use of the heart-lung bypass machine, they also increase the difficulty somewhat in performing what were already difficult and delicate anastomosis procedures that must be performed to connect the bypass graft or grafts during the CABG procedure.
The most conventional techniques for making anastomoses involve manually suturing the two tubular conduits together (e.g., manually suturing the graft to the target vessel) around an opening between them. Manual suturing is difficult, time-consuming and requires a great deal of skill and manual dexterity on the part of the surgeon performing the anastomosis. The difficulties in performing anastomoses by manual suturing are magnified when they are done during a beating heart CABG procedure as the beating of the heart introduces perturbations that make it even more difficult to suture in a reliable, consistent and effective manner. These difficulties have largely limited CABG procedures to open surgical settings which provide sufficient surgical access and visualization to complete the delicate anastomoses.
Attempts at performing sutureless anastomoses have, to date, been fraught with problems. Various arrangements for stapling a graft to a host vessel have been proposed, as well as multi-piece compression mechanisms that aim to clamp a graft to a vessel. Some techniques have attempted to perform the procedure intravascularly, through the use of catheter-based delivery of devices and/or grafts. Other approaches have used a unitary connector which is placed partially within the lumen of a graft, and the exposed end is passed through an arteriotomy in a host vessel, and then expanded to lock the graft and host together. All of these approaches have experienced complications such as leakage at the site of the anastomosis, difficulty in the performance of the anastomosis using the techniques required for the particular technology employed, or closure of the graft much sooner than the expected lifetime of performance of the same. For end-to-side anastomoses performed which leave some amount of metal from the anastomosis device exposed to the blood flowing through the host and graft, closure problems have presented, which may be due to blood clotting in response to the exposed metal. Additionally, end-to-side anastomoses that are formed at substantially a right angle may cause turbulence in the required abrupt change in directionality that the blood must take as it flows from the host to the graft, which has been proposed as another cause of clotting/closure or possibly early stenosis. Another problem with an end-to-side anastomosis that substantially forms a right angle or approximates such an angle is the increased risk of kinking of the graft vessel that it causes.
Thus, there is a need for sutureless anastomosis devices, tools and techniques that offer a reliable alternative to suturing techniques and known sutureless techniques, and which are relatively easier to implement while giving consistent, results. It would further be desirable to provide such devices, tool and techniques that would facilitate the performance of higher quality anastomoses than those currently made and with less time required to make the anastomoses.
With continued interest and development toward CABG procedures which are even less invasive than the current techniques for beating heart CABG procedures, it will further be desirable to provide anastomosis techniques which can be performed endoscopically, with the surgeon working outside of the patient.